Fabrication of B/C/N/O/Si doped sputtering targets

ABSTRACT

The present invention relates to a method of manufacturing sputtering targets doped with non-metal components including boron, carbon, nitrogen, oxygen and silicon. A powder process is utilized whereby alloyed powders, which contain non-metal elements of B/C/N/O/Si and non-metal containing phases of less than ten microns in microstructure, are blended, canned and subjected to hot isostatic press consolidation. The sputtering targets of the present invention avoid spitting problems during sputtering of the target material on a substrate.

FIELD OF INVENTION

The invention is directed to a method of fabricating sputtering targetsdoped with non-metal additions including boron, carbon, nitrogen, oxygenand silicon by using atomized or crushed alloy powder or ultra fineboride, carbide, nitride, oxide and silicide powder and hot isostaticpressing.

BACKGROUND OF THE INVENTION

Cathodic sputtering processes are widely used for the deposition of thinfilms of material onto desired substrates. A typical sputtering systemincludes a plasma source for generating an electron or ion beam, atarget that comprises a material to be atomized and a substrate ontowhich the sputtered material is deposited. The process involvesbombarding the target material with an electron or ion beam at an anglethat causes the target material to be sputtered or eroded. The sputteredtarget material is deposited as a thin film or layer on the substrate.

The target materials for sputtering process range from pure metals toever more complicated alloys. The use of complex 3 to 6 element alloysis common in the sputtering industry. Alloying additions such as boron,carbon, nitrogen, oxygen, silicon and so on are frequently added to Cr-,Co-, Fe-based alloys and other intermetallic alloys to modifycharacteristics such as deposited film grain-size, surface energy andmagnetic properties.

The presence of non-metal additions like boron, carbon, nitrogen, oxygenand silicon to target materials is either in the form of pure elements,e.g. boron and carbon, or in the form of compounds like nitride andoxide. The pure element phases such as boron and carbon and the compoundphases like boride, carbide, nitride, oxide, and silicide, however causespitting problems during sputtering. The present invention provides asolution to this problem.

SUMMARY OF THE INVENTION

The present invention relates to a novel method of fabricatingsputtering targets that are doped with non-metals such as boron, carbon,nitrogen, oxygen and silicon or mixtures thereof or compounds ofnon-metals. The process comprises preparation of a pre-alloyed powder orselection of ultra fine compound powder of less than 10 microns,preferably less than 5 microns and most preferably less than 2 microns.It has been discovered that spitting will not occur when the abovephases are in form of ultra fine particles of less than 10 microns insize. After the ultra fine powders are blended together, the powderblend is canned, followed by a hot isostatic press (HIP) consolidation.Powder processing as above is employed to make the target materialsbecause of unique advantages over the prior art's melting process, bothtechnically and economically. These and other objectives of thisinvention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying drawing wherein:

FIG. 1 shows the process flow chart of the invention described herein.

DETAILED DESCRIPTION OF THE INVENTION

The alloy powders of the present invention include alloys andintermetallic alloys composed of 2 to 6 elements, including but notlimited to Cr-, Co-, Ru-, Ni-, or Fe-based alloys. The alloy powderscontain Cr, Co, Ru, Ni, or Fe, optionally alloyed with each other, orwith Cr, Al, Pt, Ta, Zr, Mo, Ti, V or W, and include at least onenon-metallic addition selected from B, C, N, O or Si.

FIG. 1 shows the process flow for making the targets. The first step isthe preparation of raw material powders like atomized alloy powders ofNi—Al—B, Fe—B, Fe—C, Fe—Si and so on or the selection of commerciallyavailable ultra fine compound powders such as Al₂O₃, AlN, MoB and Cr₂O₃of 10 microns or less. Atomized powders have very fine microstructurebecause of extremely quick cooling and solidification, therefore it isthe first choice as raw materials. In some cases powders of finemicrostructures can also be made by melting and mechanically crushingingots much more economically than by atomization, especially for smallquantities of powder. Some ultra fine compound powders like Al₂O₃, AlN,MoB, Cr₂O₃, B₄C and so on are also commercially available, and thereforesave both time and money for new product development. Blending ofvarious powders together is preferable because segregation occurs quiteoften, especially when powders of differing particle size and gravityare combined. Special blending and homogenizing methods include ballmilling, v-blending, tubular blending, and attritor milling. Therefore,it is preferred that the alloy powders and/or mixture be substantiallyhomogeneous for best results.

Proper canning techniques are needed to avoid segregation duringcanning. The powders are canned in preparation for consolidation. Incanning for example, a container is filled with the powder, evacuatedunder heat to ensure the removal of any moisture or trapped gassespresent, and then sealed. Although the geometry of the container is notlimited in any manner, the container can possess a near-net shapegeometry with respect to the final material configuration.

The encapsulate material from the canning step is then consolidated viaHot-Isostatic-Pressing (HIP), a procedure known in the art. A HIP unitis typically a cylindrical pressure vessel large enough to house one ormore containers. The inner walls of the vessel can be lined withresistance heating elements, and the pressure can be controlled by theintroduction of inert gas within the container. HIP parameters includingtemperature, pressure and hold time will be minimized to prevent thegrowth of compound phases and grain size, as well as to save energy andto protect the environment. Pressures of about 5 to about 60 ksi(preferably 10-20 ksi) at temperatures between about 500° C. to about1500° C. (preferably 600-900° C.) are typically employed to achieveappropriate densities. Depending upon the complexity of the cycle, totalhold times during isostatic pressing typically vary from about 0.5 toabout 12 hours. It is noteworthy that other powder consolidationtechniques such as hot pressing and cold pressing can also be employedindependently or in conjunction with HIP processing.

After consolidation, the solid material form (billet) is removed fromthe encapsulation can, and a slice of the billet can then be sent to betested as to various properties of the billet. If desired, the billetcan be subjected to optional thermo-mechanical processing to furthermanipulate the microstructural and macro-magnetic properties of thetarget. Also, the final shape and size of the sputter targets can beformed, for example, by processes such as wire EDM, saw, waterjet,lathe, grinder, mill, etc. In these steps, the target can be cleaned andsubjected to a final inspection.

TABLE 1 alloys manufactured using the method described herein. MaterialsTypical Chemistry Co—Cr—Pt—B Co61 at %-Cr15 at %-Pt12 at %-B12 at %Co—Cr—Pt—O—Si Co56 at %-Cr18 at %-Pt16 at %-O3.33 at %-Si1.67 at %Co—Pt—B—C Co60 at %-Pt20 at %-B16 at %-C4 at % Co—Ta—N Co50 at %-Ta50 at% doped with nitrogen of 5000 ppm Co—Ta—Zr—O—Si Co85 at %-Ta5 at %-Zr5at %-O3.33 at %-Si-1.67 at % Co—Ti—Pt—B Co62 at %-Ti6 at %-Pt12 at %-B20at % Cr—B Cr97 at %-B3 at % Cr—Mo—B Cr80 at %-Mo15 at %-B5 at % Cr—Mo—OCr80 at %-Mo20 at % doped with oxygen of 6000 ppm Cr—O Cr doped withoxygen of 5000 ppm Cr—Ti—B Cr80 at %-Ti16 at %-B4 at % Cr—V—O Cr80 at%-V20 at % doped with oxygen of 4000 ppm Cr—V—Zr—O Cr79 at %-V20 at%-Zr1 at % doped with oxygen of 4000 ppm Cr—W—O Cr90 at %-W10 at % dopedwith oxygen of 6000 ppm Cr—Zr—O Cr99 at %-Zr1 at % doped with oxygen of4000 ppm Fe—Co—B Fe56 at %-Co31 at %-B11 at % Fe—Si—Al Fe73 at %-Si17 at%-Al10 at % (Sendust) Fe—Ta—C Fe80 at %-Ta8 at %-C12 at % Ni—Al—B Ni50at %-Al50 at % doped with boron of 2500 ppm Ni—Al—N Ni48 at %-Al48 at %doped with nitrogen of 4 at % Ni—Al—O Ni50 at %-Al50 at % doped withoxygen of 5000 ppm Ru—Al—O Ru50 at %-Al50 at % doped with oxygen of 5000ppm Ru—Al—N Ru50 at %-Al50 at % doped with nitrogen of 4000 ppm

EXAMPLES

The following examples demonstrate the present invention further, butshould not be construed as a limitation of the present invention. Theprocesses for all materials are similar with each other as shown in FIG.1, and the main differences are various combinations of raw materials(powders).

EXAMPLE 1 Production of Cr-Mo Based Sputtering Target With BoronContent—Cr80at %-Mo15at %-B5at %

The above alloy is made with the following powder blends, (1) Cr, Mo andultra fine MoB compound powder, and (2) Cr, Mo and pre-alloyed Cr-3.1wt% B powder that is made with a vacuum induction melter at 1730° C. andmechanically crushing cast ingots into powder at room temperature.Special attention must be paid to mixing all powders together when ultrafine compound powder like MoB is used, otherwise segregation may occur.Herewith an attritor mill or a ball mill must be used for blending from2 to 24 hours. The HIP parameters for this kind of alloy include thetemperature ranging from about 1000-1400° C., at a pressure from about5-40 ksi and a hold time from about 1-12 hours. The cooling rate must becontrolled too, otherwise the HIPed billet may crack during coolingdown. A cooling rate of 3° C./min and a hold plateau at 800° C. for 6hours is introduced to cooling phase.

EXAMPLE 2 Production of Co—Cr—Pt Based Sputtering Target With Si and OContent—Co56at %-Cr18at %-Pt16at %-O3.33at %-Si1.67at %

Two different combinations of starting powders are employed herein. Thefirst is the combination of Co, Cr, Pt and ultra fine SiO₂ powder andthe second is the combination of Co, Cr, Pt, atomized Co—Si pre-alloyand ultra fine Cr₂O₃ powder. The suicides are ultra fine and welldispersed in Co matrix of original gas-atomized Co—Si particles. Specialmixing methods using an attritor mill or a ball mill for 2 to 24 hoursmust be employed here to mix all powders together homogeneously whenultra fine compound powders like SiO₂ and Cr₂O₃ are used, otherwisesegregation may occur. The HIP parameters for this kind of alloy includethe temperature ranging from about 600-1400° C., at a pressure fromabout 5-40 ksi and a hold time from about 1-12 hours.

EXAMPLE 3 Production of Cr—X (Wherein X is Mo, W, V, Ti, Zr, Ta, orMixtures Thereof) Sputtering Target Doped With Oxygen—Cr80at %-Mo20at %Doped With Oxygen of 6000 ppm

Regular Cr, Mo and partly oxidized Cr powder of oxygen level 15000 ppmare used to make the targets. The Cr powder of high oxygen is producedby oxidizing Cr flakes at high temperature and then subjected tomechanical crushing. In this case, only a part of the surface area of Crpowder is covered with oxides. Special attention must be paid to Crpowder of high oxygen level and mixing all powders together in thiscase, otherwise segregation may occur. Herewith an attritor mill or aball mill may be used for blending from 2 to 24 hours. The HIPparameters for this kind of alloy include the temperature ranging fromabout 800-1400° C., at a pressure from about 5-40 ksi and a hold timefrom about 1-12 hours. The cooling rate must be controlled too,otherwise the HIPed billet may crack during cooling down. A cooling rateof 3° C./min and a hold plateau at 800° C. for 6 hours is introduced tocooling phase.

EXAMPLE 4 Production of NiAl Sputtering Target Doped With Boron, Oxygenor Nitrogen—Ni50at %-Al50at % Doped With Boron of 2500 ppm

Gas-atomized NiAl intermetallic powder and ultra fine Al₂O₃ and AlNpowder of less than 5 microns in diameter were taken for making NiAlsputtering targets doped with oxygen or nitrogen. Besides gas-atomizedNiAl powder, boron-doped gas-atomized NiAl powder was also taken formaking NiAl sputtering targets doped with boron and borides are ultrafine and well dispersed in the matrix. Conventional gas atomizationmethods are used to manufacture the powders. Special attention must bepaid to mixing all powders together when ultra fine compound powderslike Al₂O₃ and AlN are used, otherwise segregation may occur. Herewithan attritor mill or a ball mill may be used for blending from 2 to 24hours. The HIP parameters for this kind of alloy include the temperatureranging from about 900-1400° C., at a pressure from about 5-40 ksi, anda hold time from about 1-12 hours. The cooling rate must be controlledtoo, otherwise the HIPed billet may crack during cooling down. Apower-off furnace cooling and a hold plateau at 700° C. for 4 hours isintroduced to cooling phase.

While this invention has been described with reference to severalpreferred embodiments, it is contemplated that various alterations andmodifications thereof will become apparent to those skilled in the artupon a reading of the detailed description contained herein. It istherefore intended that the following claims are interpreted asincluding all such alterations and modifications as fall within the truespirit and scope of this invention.

1. A method of fabricating sputter targets doped with containing anon-metallic addition, the method comprising the steps of: (a) preparingor selecting raw material elemental powders, wherein the powders areselected from the group consisting of Cr-, Co-, Ru-, Ni- and Fe-based oralloys which are doped with contain at least one non-metal selected fromthe group consisting of boron, carbon, oxygen and nitrogen, wherein thepowders have microstructures of less than about 10 microns; (b) canning;(c) hot isostatic pressing; and (d) machining to form a sputter target.2. The method according to claim 1, wherein the elemental powders oralloys have microstructures that are substantially homogeneous.
 3. Themethod according to claim 1, wherein the powders have microstructuresless than 5 microns.
 4. The method according to claim 1, wherein thepowders have microstructures less than 2 microns.
 5. The methodaccording to claim 1, wherein the hot isostatic pressing is conducted ata temperature between 500° C. to about 1500° C., a pressure between 5 toabout 60 ksi and for a time between 0.5 to 12 hours.
 6. The methodaccording to claim 1, wherein the sputter target contains Fe—Co dopedwith boron.
 7. The method according to claim 6, wherein the sputtertarget contains Fe56at %, Co31at %, and B11at %.
 8. The method accordingto claim 1, wherein the sputter target material contains RuAl doped withoxygen or nitrogen.
 9. The method according to claim 8, wherein thesputter target contains Ru50at %-Al50at %, doped with oxygen of 5000ppm.
 10. The method according to claim 8, wherein the sputter targetcontains Ru50at %-Al50at %, doped with nitrogen of 4000 ppm.
 11. Themethod according to claim 1, wherein the sputter target materialcontains NiAl doped with oxygen, nitrogen or boron.
 12. The methodaccording to claim 11, wherein the sputter target material containsNi50at %-Al50at % doped with boron of 2500 ppm.
 13. The method accordingto claim 11, wherein the sputter target material contains Ni50at%-Al50at % doped with N4at %.
 14. The method according to claim 11,wherein the sputter target material contains Ni50at %-Al50at % dopedwith oxygen of 5000 ppm.
 15. The method according to claim 1, whereinthe sputter target material contains Cr—Mo doped with boron or oxygen.16. The method according to claim 15, wherein the sputter targetmaterial contains Cr80at %-Mo15at % doped with B5at %.
 17. The methodaccording to claim 15, wherein the sputter target material containsCr80at %-Mo20at % doped with oxygen of 6000 ppm.
 18. The methodaccording to claim 1, wherein the sputter target material contains Cr—Tidoped with boron or oxygen.
 19. The method according to claim 18,wherein the sputter target material contains Cr80at %-Ti16at % dopedwith B4at %.
 20. The method according to claim 1, wherein the sputtertarget material contains Co—Cr—Pt doped with boron, silicon, carbon,oxygen or mixtures thereof.
 21. The method according to claim 20,wherein the sputter target material contains Co61at %-Cr15at %-Pt12at %doped with B12at %.
 22. The method according to claim 20, wherein thesputter target material contains Co56at %-Cr18at %-Pt16at % doped withO3.33at %-Si1.67at %.
 23. The method according to claim 1, wherein theraw material powders are selected from the group consisting of Cr-, Co-,Ru-, Ni- and Fe-based alloys, are optionally alloyed with each other, orwith Cr, Al, Pt, Ta, Zr, Mo, Ti, V, Si or W, and further contains atleast one non-metallic addition selected from the group consisting of B,C, N, O and Si .
 24. A sputter target containing a non-metallicaddition, the sputter target being formed by (a) preparing or selectingraw material powders, wherein the powders are selected from the groupconsisting of Cr-, Co-, Ru-, Ni- and Fe-based alloys which contain atleast one non-metal selected from the group consisting of boron, carbon,oxygen and nitrogen, wherein the powders have microstructures of lessthan about 10 microns, (b) canning the raw material powders; (c) hotisostatic pressing the canned raw material powders to form a billet; and(d) machining the billet to form the sputter target.
 25. The sputtertarget according to claim 24, wherein the powders have microstructuresthat are substantially homogeneous.
 26. The sputter target according toclaim 24, wherein the powders have microstructures less than 5 microns.27. The sputter target according to claim 24, wherein the powders havemicrostructures less than 2 microns.
 28. The sputter target according toclaim 24, wherein the hot isostatic pressing is conducted at atemperature between 500° C. to about 1500° C., a pressure between 5 toabout 60 ksi and for a time between 0.5 to 12 hours.
 29. The sputtertarget according to claim 24, wherein the sputter target contains Fe—Codoped with boron.
 30. The sputter target according to claim 29, whereinthe sputter target contains Fe56at%, Co31at%, and B11at%.
 31. Thesputter target according to claim 24, wherein the sputter targetcontains RuAl doped with oxygen or nitrogen.
 32. The sputter targetaccording to claim 31, wherein the sputter target contains Ru 50at%-Al50at%, doped with oxygen of 5000 ppm.
 33. The sputter target accordingto claim 31, wherein the sputter target contains Ru 50at%-Al 50at%,doped with nitrogen of 4000 ppm.
 34. The sputter target according toclaim 24, wherein the sputter target contains NiAl doped with oxygen,nitrogen or boron.
 35. The sputter target according to claim 34, whereinthe sputter target contains Ni50at%-Al50at% doped with boron of 2500ppm.
 36. The sputter target according to claim 34, wherein the sputtertarget contains Ni50at%-Al50at% doped with N4at%.
 37. The sputter targetaccording to claim 34, wherein the sputter target containsNi50at%-Al50at% doped with oxygen of 5000 ppm.
 38. The sputter targetaccording to claim 24, wherein the sputter target contains Cr—Mo dopedwith boron or oxygen.
 39. The sputter target according to claim 38,wherein the sputter target contains Cr80at%-Mo15at% doped with B5at%.40. The sputter target according to claim 38, wherein the sputter targetcontains Cr80at%-Mo20at% doped with oxygen of 6000 ppm.
 41. The sputtertarget according to claim 24, wherein the sputter target contains Cr—Tidoped with boron or oxygen.
 42. The sputter target according to claim41, wherein the sputter target contains Cr80at%-Ti16at% doped withB4at%.
 43. The sputter target according to claim 24, wherein the sputtertarget contains Co—Cr—Pt doped with boron, carbon or mixtures thereof.44. The sputter target according to claim 43, wherein the sputter targetcontains Co61at%-Cr15at%-Pt12at% doped with B12at%.
 45. The sputtertarget according to claim 24, wherein the group consisting of Cr-, Co-,Ru-, Ni- and Fe-based alloys are optionally alloyed with each other, orwith Cr, Al, Pt, Ta, Zr, Mo, Ti, V, Si or W.